To deal with the issue on Windows OS, you would have to defragment your HDD, but can you defrag a Mac? Does Defragmentation for Mac Work? These include scattered empty clusters on the hard disk that had appeared as a result of multiple reads and writes performed. Bogged down performance can be caused by a number of reasons. However, despite being considered close to computer perfection, Macs are not immune to slow-downs. Delivering speedy and smooth performance, Macs are known to be fast and reliable.